--- a/enumerator.cabal
+++ b/enumerator.cabal
@@ -152,2 +152,5 @@ library
 
+  if !impl(ghc >= 8.0)
+    build-depends: semigroups == 0.18.*
+
   exposed-modules:
--- a/lib/Data/Enumerator/Internal.hs
+++ b/lib/Data/Enumerator/Internal.hs
@@ -50,2 +50,3 @@ import           Data.Function (fix)
 import           Data.Monoid (Monoid, mempty, mappend, mconcat)
+import qualified Data.Semigroup as S
 
@@ -73,2 +74,6 @@ instance Monad Stream where
 
+instance S.Semigroup (Stream a) where
+	(<>) (Chunks xs) (Chunks ys) = Chunks (xs ++ ys)
+	(<>) _ _ = EOF
+
 instance Monoid (Stream a) where